The pilot's handbook of aeronautical knowledge introduces pilots to the broad spectrum of aeronautical knowledge that will be needed as they progress in their pilot training.

Wednesday, October 7, 2009

Effects and Use of the Controls

In explaining the functions of the controls, the instructor should emphasize that the controls never change in the results produced in relation to the pilot. The pilot should always be considered the center of movement of the airplane, or the reference point from which the movements of the airplane are judged and described. The following will always be true, regardless of the airplane’s attitude in relation to the Earth.

When back pressure is applied to the elevator control, the airplane’s nose rises in relation to the pilot.

When forward pressure is applied to the elevator control, the airplane’s nose lowers in relation to the pilot.

When right pressure is applied to the aileron control, the airplane’s right wing lowers in relation to the pilot.

When left pressure is applied to the aileron control, the airplane’s left wing lowers in relation to the pilot.

When pressure is applied to the right rudder pedal, the airplane’s nose moves (yaws) to the right in relation to the pilot.

When pressure is applied to the left rudder pedal, the airplane’s nose moves (yaws) to the left in relation to the pilot.

The preceding explanations should prevent the beginning pilot from thinking in terms of “up” or “down” in respect to the Earth, which is only a relative state to the pilot. It will also make understanding of the functions of the controls much easier, particularly when performing steep banked turns and the more advanced maneuvers. Consequently, the pilot must be able to properly determine the control application required to place the airplane in any attitude or flight condition that is desired.

The flight instructor should explain that the controls will have a natural “live pressure” while in flight and that they will remain in neutral position of their own accord, if the airplane is trimmed properly.

With this in mind, the pilot should be cautioned never to think of movement of the controls, but of exerting a force on them against this live pressure or resistance. Movement of the controls should not be emphasized; it is the duration and amount of the force exerted on them that effects the displacement of the control surfaces and maneuvers the airplane.

The amount of force the airflow exerts on a control surface is governed by the airspeed and the degree that the surface is moved out of its neutral or streamlined position. Since the airspeed will not be the same in all maneuvers, the actual amount the control surfaces are moved is of little importance; but it is important that the pilot maneuver the airplane by applying sufficient control pressure to obtain a desired result, regardless of how far the control surfaces are actually moved.

The controls should be held lightly, with the fingers, not grabbed and squeezed. Pressure should be exerted on the control yoke with the fingers. A common error in beginning pilots is a tendency to “choke the stick.” This tendency should be avoided as it prevents the development of “feel,” which is an important part of aircraft control.

The pilot’s feet should rest comfortably against the rudder pedals. Both heels should support the weight of the feet on the cockpit floor with the ball of each foot touching the individual rudder pedals. The legs and feet should not be tense; they must be relaxed just as when driving an automobile.

When using the rudder pedals, pressure should be applied smoothly and evenly by pressing with the ball of one foot. Since the rudder pedals are interconnected, and act in opposite directions, when pressure is applied to one pedal, pressure on the other must be relaxed proportionately. When the rudder pedal must be moved significantly, heavy pressure changes should be made by applying the pressure with the ball of the foot while the heels slide along the cockpit floor. Remember, the ball of each foot must rest comfortably on the rudder pedals so that even slight pressure changes can be felt.

In summary, during flight, it is the pressure the pilot exerts on the control yoke and rudder pedals that causes the airplane to move about its axes. When a control surface is moved out of its streamlined position (even slightly), the air flowing past it will exert a force against it and will try to return it to its streamlined position. It is this force that the pilot feels as pressure on the control yoke and the rudder pedals.